Only had it a week and need more power

[inv3ctiv3]

So I've been riding a lot, like 3-4 times a week and feel pretty comfortable on the quad but on yesterdays trail ride I could really feel the engine being restricted when I was WOT. It's got great low-mid range power but up top you really feel how restricted the motor is.

Right now the quad is totally stock and I don't want to do any internal engine work at the moment so I am looking at pipe (looking for recommendations on a good but not super expensive pipe), air filter, removing the airbox lid and jetting.

Now I have owned lots of ATV's and ATC's but have never had to re-jet any of them because I don't generally mod them so I really need help with that. I'll be riding in the mountains of CA and around sea level. And because the trails I ride go so far back and are so un-reachable by a truck I need this to be just as reliable as it is stock. I need it to be able to start up just like it does so I am really looking to you carb/jet experts out there.

[TRXRacer1]

Truth is just about anything is going to give you similar gains. The head pipe is great until you do extensive internal work so find a good deal on a slip-on and enjoy. If you don't care about name brands check out Lexx from RMATV. What ever you do don't buy a jet kit, you already have a great adjustable needle. RMATV also has great prices on mains and pilots so you're better off get a few in the range you'll be jetting in. A 40 pilot and a some mains from 160-180 will run you around $20 from there and cover anything you do. Someone will do it so I'll warn you now, people who suggest a 42 for this job do not understand that with a turn of the mix screw you can find the perfect pilot circuit mix for anything you do with this project.

I know what the 350x is like and if you're still running a stock can on the 400ex then you will be happy with an aftermarket slip-on. Instant difference.

[honda400ex2003]

soothing isnt it... I love the hundy :cool: steve

[inv3ctiv3]

Any other suggestions on slip ons or is the LEXX the best bang for the buck?

[honda400ex2003]

my .02 is t-4 but the lexx is becoming a close third after the q4 for the quiet aspect. steve

[a4guy]

I myself have the t-4 and could not be happier with it. Love the sound and gave me a nice bit of snort after adding it and jetting.

[bkelley]

I'd have to agree with the Lexx being the best bang for the buck. $200 for a fully tunable slip-on is nice.

[HondaRacing83]

lexx is very good,but theres the CZR slip on,look it up on ebay,$139 buy it now with $20 shipping,its got a nice sound but its like 100db so its loud also

[bkelley]

Originally posted by HondaRacing83
lexx is very good,but theres the CZR slip on,look it up on ebay,$139 buy it now with $20 shipping,its got a nice sound but its like 100db so its loud also First hit on google was a thread on thumper talk talking about them being pretty crappy. I'd stay away.

http://www.thumpertalk.com/forum/archive/index.php/t-440381.html

[inv3ctiv3]

My list of mods before my race are:
Lexx Slip On
Uni Filter (it already has a big yellow filter but rather get a new one)
Get it jetted
Remove Airbox lid
450R Shocks (should I do anything with the rear shock?)
AC Nerf Bars
Tether Kill Switch
And install my CNC Steering Stabilizer

[bkelley]

The rear shock is fine, just make sure to adjust the ride height and sag. The 450r shocks along with the CNC stabilizer will make it ride like a completely different machine. You're going to love it.

[TRXRacer1]

Originally posted by bkelley
The rear shock is fine, just make sure to adjust the ride height and sag. X2

[inv3ctiv3]

Ah can't wait to get those shocks! haha

[inv3ctiv3]

I've also noticed the bike kinda squeeks now that I wash it, what should I lube it with? Any certain kind of grease?

[RYLAND839]

One thing the 400ex has is a restricted CDI box. It controls the timing and max RPM. Once I changed to a K&N filter rejetted the carb with a Stage3 Dyno-jet kit cleaned out the poor welding in the header and put an AMR stage2 CDI box and Monster Coil It woke up the top end. I did all this for about $150. These were all easy upgrades for me to do as I had never owned a quad before this one. Of course now that I have been riding it this way for almost two years it is time to really wake it up.

I have been buying up a part here and a part there for the last year and am just about to upgrade it to a 440. Last item to get before the build is a new exhaust. It is a big struggle. A couple of my favorite places to ride are restricted to 93db. Once I figure out what exhaust I can get that will be able to keep me below that when I am there and still able to easily change configuration for areas less restricted on noise levels I will begin the build.

[RYLAND839]

One thing the 400ex has is a restricted CDI box. It controls the timing and max RPM. Once I changed to a K&N filter rejetted the carb with a Stage3 Dyno-jet kit cleaned out the poor welding in the header and put an AMR stage2 CDI box and Monster Coil It woke up the top end. I did all this for about $150. These were all easy upgrades for me to do as I had never owned a quad before this one. Of course now that I have been riding it this way for almost two years it is time to really wake it up.

I have been buying up a part here and a part there for the last year and am just about to upgrade it to a 440. Last item to get before the build is a new exhaust. It is a big struggle. A couple of my favorite places to ride are restricted to 93db. Once I figure out what exhaust I can get that will be able to keep me below that when I am there and still able to easily change configuration for areas less restricted on noise levels I will begin the build.

[TRXRacer1]

In all reality the CDI is the last thing he needs to worry about right now. That would do nothing for what he's got.

[inv3ctiv3]

Yea like I said I just want to do simple reliable mods. I just got the following stuff:

CNC Steering Stabilizer
CYCRA Hand Guards
AC Nerf Bars

Next up:
450R shocks (or Elka's)
LEXX Slip On
UNI Filter
Re-jet
Tether Kill Switch

[RYLAND839]

Originally posted by TRXRacer1
In all reality the CDI is the last thing he needs to worry about right now. That would do nothing for what he's got.

interesting.... I did these changes to solve the very issue he was addressing. All for around $150. The REV-Limiter on the stock CDI is way too constrictive. Also changing the gearing to the type of riding he is doing will help tremendously. The addition of an aftermarket pipe is good and the Lexx seems to be a great choice from what I have read. I chose not to upgrade the exhaust at the time I was doing my other mods just to see where it would put me. I was easily pulling away from piped and jetted 400EX quads on hill climbs as well as in the flats. Bored 400EXs, that are ported and polished, are a completely different story. If he pulls his header off and inspects the pipe he will see that the welds at the engine end of the pipes constrict the air-flow terribly and can be ground down to improve air-flow as well.

This is my opinion based on my experiences.

[honda400ex2003]

CDIs are a waste of money along with coils! steve

[JOHNDOE83]

Originally posted by honda400ex2003
CDIs are a waste of money along with coils! steve

Coils are a waste of money.

But cdi's are a good buy, but only if you have mods that need the cdi.

Cdi's that are a waste of money= procom, magnum, amr, big gun....Ive tried all of these, the best CDI by far is the white bros.

CDI's have different timing curves, if you buy one that isnt what you need then it will be pointless even hurt performance.

After I did a few major mods, I was able to hit the limiter and it would come in way to early, after some CDI testing the white bros cdi has shown to be the best.

The vast majority of small bores 416, 426, cams, pipes...etc. still dont hit the limiter very easily, but when you get into big bores, carbs...etc. the cdi comes in handy.

Unless your racing I wouldnt buy one, if you are gonna buy one, get the white bros.

Tire size and sproket size play a major role in the limiter also, if you dont have the power to pull your tires and gearing, youll never hit the limiter and never even get to top speed.